Fix typo in command.rb:115

The Hash key `cut_errors` should be `cur_errors`
Added a spec to validate that Command#add_error properly creates nested Hashes
Merge pull request #39 from rks/master

Fix typo in command.rb:115
Added tests for StringFilter :strict option.
Merge pull request #41 from ehalferty/master

Added tests for StringFilter :strict option.
Merge github.com:cypriss/mutations